Income Taxes - Summary of Reconciliation of Unrecognized Tax Benefits (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Beginning of fiscal year	$ 1,300	$ 1,435	$ 1,564
Increases in tax positions for prior years	43	27	5
Decreases in tax positions for prior years	(1)	(278)	(3)
Increases in tax positions for current year	149	122	72
Lapse of the statute of limitations	(275)	(6)	(203)
End of fiscal year	$ 1,216	$ 1,300	$ 1,435